Impact of Fin Doping and Gate Stack on FinFET (110) and (100) Electron and Hole Mobilities

摘要

Double-gate FinFET $(hbox{110})langle hbox{110}rangle$ and $(hbox{100})langle hbox{100}rangle$ electron mobility $(mu_{e})$ and hole mobility $(mu_{h})$ are experimentally investigated for the following: 1) a wide range of boron and phosphorus fin doping concentrations and 2) a wide variety of gate stacks combining $hbox{HfO}_{2}$, $hbox{SiO}_{2}$, or SiON insulators with TiN or poly-Si electrodes. It is found out that, irrespective of fin doping and gate stack, $(hbox{110})langlehbox{110}rangle mu_{e}$ is competitive with the $(hbox{100})langlehbox{100}rangle mu_{e}$, while $(hbox{110})langlehbox{110}rangle mu_{h}$ is $geq hbox{2} times$ higher than $(hbox{100})langlehbox{100}rangle mu_{h}$. Inversion $ mu_{e}$ and $mu_{h}$ are independent of doping as long as the effective field/doping combination enables the screening of the depletion charge. Mobility degradation with doping is significantly lower in accumulation mode (AM) than in inversion mode (IM) such that, for heavily B-doped fins, AM hole mobility exceeds the IM electron mobility even in (100) FinFETs. In undoped fins, AL-n TiN gate stress is observed to improve $mu_{e}$  for both orientations without degrading $mu_{h}$.